threatened species.
Three independent processes have, however, resulted in a substantial degeneration of the montados and dehesas in Portugal and Spain. One of them has been triggered by the 'wheat campaign' of the 1930s. Because of the emphasis on crop cultivation, the trees on the montados were reduced to a minimum, and mechanisation plus fertilisation was increased. While the oaks were severely affected by mechanised work and use of chemicals, the poor soils did not allow crop yields to be economically successful. Consequently, large portions of the land were abandoned in favour of establishing large-scale monoculture of fast-growing eucalyptus, designated for the cellulose industry. This development led to irreversible transformations and deteriorations of the landscape (Pinto Correia, 1991), accompanied by a loss of biological diversity that has affected regional socio-economic structures. Today, there is an increasing awareness that traditional forms of land management need to be re-established by increasing goat production, improving pastures and protecting and planting more cork oaks. The dehesa/montado is the typical candidate for a Red Book of threatened landscapes (Naveh, 1993). See also Chapter 23 (Box 23B).